There are over 46,000 different species of spiders across the world, with only a very small number – around 30 – considered animals dangerous to humans. Below we discuss the most dangerous and most venomous spiders in the world.
All spiders are predators, typically with an insect-based diet, though there are some notable exceptions. Many spiders hunt by using their fangs to inject venom into their prey, and it is a subset of these spiders that can be dangerous – in some cases fatal – to humans.
Spider venom has evolved to paralyse and kill smaller animals than humans, and most spiders are either too small to be able to puncture human skin, or not aggressive enough to attempt it. For those spiders that are able to bite humans, the majority rarely cause injuries more significant than a mosquito bite.
However, there are a handful of spiders with venom so potent a single bite can kill a person. Whilst ‘death by spider bite’ does happen, it’s very rare – with an estimated seven human deaths each year – as most clinics and hospitals now have species-specific antivenin (antitoxin) to treat a potentially harmful spider bite correctly. So even though there are some killer spiders on this list, they’re a long way off being the most dangerous animals in the world.
Similar to our article on venomous snakes, alongside potency of venom we’ve also tried to take into account the amount of venom the spider injects when biting, as well as how aggressive they are, and how likely you are to encounter one.
With this context in mind, let’s now look at 15 of the most dangerous spiders in the world:
Yellow sac spider
The yellow sac spider doesn’t look particularly dangerous but is capable of delivering a nasty bite. These tiny spiders (0.5-1 cm) have many species that are found around the world in all continents except Antarctica.
The venom of the yellow sac spider is a cytotoxin, meaning it can break down cells and ultimately kill the area of flesh around a bite, though this outcome is very rare. Their bite is often compared to that of a brown recluse, though is less severe, with the blister or sore from a bite healing more quickly.
Brazilian Wandering Spider
Brazilian Wandering Spiders get their name from their behaviour of wandering around the jungle floor by night, and instead of having a web, resting in the day time in banana plants or termite mounds. Its Latin name comes from the Greek for murderess (Phoneutria), which suggests they are pretty deadly.
Brazilian Wandering Spiders are sometimes said to have the world’s most toxic spider venom, based on a study where mice were killed with an injection of just 0.006 mg of venom. Other sources suggest that only 2% of bites from these spiders result in the need for anti-venom as a treatment. The truth is that the venom of the Brazilian Wandering spider is extremely potent, but it’s not particularly good at injecting it into humans. Still, it’s definitely one to steer clear of!
Wolf spiders are part of the Lycosidae family of spiders, found all around the world – even in the Arctic Circle. Most wolf spiders have a broad, hairy body that’s 2-3 centimeters long and stout legs that are about the same length as their body.
They are named wolf spiders because of their hunting technique of a speedy chase then pouncing on their prey. A bite from a wolf spider can lead to dizziness and nausea, and the size of their fangs can cause trauma around the area of the bite, but they are not overly harmful to humans.
Goliath Birdeater Tarantula
The Goliath birdeater tarantula is found in northern South America, and is the largest spider in the world – by both weight (up to 175 grams) and body size (up to 13 centimeters).
Despite its cool name, this spider mainly feeds on insects, though will hunt small rodents, frogs, and lizards opportunistically. It’s certainly scary looking, with good sized fangs, but their venom is actually relatively harmless to humans, comparable to a wasp sting.
Found in all warm deserts and scrublands in all continents except Australia, the camel spider is not actually venomous. Nor is it a spider, but it is an arachnid that looks ferocious and is the stuff of legends.
During the 2003 Iraq war of rumours started to circulate about the camel spider; a spider that ate camels and sleeping sodiers from the inside out. Thankfully the rumours were exactly that, and whilst camel spiders do use digestive fluids to liquefy their victims’ flesh, and have jaws one third the size of their 15 centimeters body length, they are not dangerous to humans. A very painful bite, yes, but no venom, and certainly no death!
Fringed Ornamental Tarantula
The classic spider from an arachnophobe’s nightmare, the fringed ornamental tarantula is a big hairy beast. Unlike the other, smaller spiders on this list, tarantulas have fangs that point downwards and need to be stabbed into their prey, rather than the more common pincher-like fangs.
Most tarantula bites are about as painful (and dangerous) as a wasp sting, but these fringed orientals are renowned for their excruciatingly painful bites. They won’t kill a human but will cause significant pain, along with extreme muscle cramps and spasms. Another non-fatal spider it makes sense to steer well clear of.
Six-eyed Sand Spider
The six-eyed sand spider lives in the deserts of Southern Africa. It’s closely related to the deadly recluse spiders, and its Latin name (Sciarius) means murderer. It hunts by burrowing into the sand launching itself at unsuspecting prey.
Their venom is a powerful cytotoxin, able to kill a rabbit in 5 hours. The venom is both hemolytic and necrotic, meaning it causes blood vessels to leak and flesh to decay and die. Despite these deadly-sounding facts, there have been very few spider bites attributed to the six-eyed sand spider, perhaps because it lives in deserts that are inhospitable to humans. So it’s dangerous, but not a big killer.
Australi has a reputation for poisonous and venomous creatures, and the soft, furry mouse spider doesn’t disappoint.
Their venom is on a par with Australia’s funnel-web spider, and if bitten similar symptoms can be expected – XXX. Despite their huge fangs and dangerous venom, the mouse spider is known for its dry bites – biting with no venom – and is not particularly aggressive, hence its lower place on this list.
The hobo spider has a body that grows up to 1.5 centimeters, supported by spindly looking brown with hairy legs.
Whilst not fatal, these spiders have a nasty necrotic venom similar to recluse spiders.
A bite from the hobo spider will likely cause a severe headache and an open wound that takes a long time to heal. It makes this list of deadliest spiders as it’s both common in North America and Europe, and relatively aggressive for a spider, so watch out!
Brown recluse spider
The brown recluse spider is found in the warmer parts of much of the southern USA, where it also goes by the names spiders, fiddle-backs, or reapers. They are generally found in caves, rodent burrows, and other sheltered environments, including. undisturbed spaces in buildings, such as attics, walls, and ceilings.
Although they are relatively shy, have small fangs, and are not particularly aggressive, their venom is known to be necrotic – meaning flesh-eating. A bite from the brown recluse spider can lead to a condition called loxoscelism where a deep open sore forms and the skin around the bite begins to die. There’s no good treatment for this condition, which can lead to skin grafts being needed, or in particularly bad cases, amputation.
Brown Widow Spider
The brown widow spider was originally native to Africa, but has found its way around the world to most continents where it lives in warm climates in buildings, old tires, and shrubs.
It’s not an aggressive spider species, and only injects a small amount of venom when it bites, but on the flip side has venom that’s twice as potent as the black widow. This spider is quite capable of killing a human with one bite.
Red Widow Spider
The red widow, or red-legged widow, is distinguished from other widow spiders by its reddish tinge and reddish-brown to black abdomen. As with other widow species, the female is much larger than the male (typically with 5-6 centimeter leg span), and usually kills and eats the male after mating.
This spider is endemic to central and southern Florida, where it lives on insects. It is not considered aggressive, with very few bites on humans reported, but has similar venomous to the black widow. This means red widow spider bites can result in death, if not treated with anti-venom.
Black Widow Spider
Found in the US and parts of Canada and Latin America, the black widow is one of the world’s most dangerous spiders. Not only does the female have a venom that’s around 15 times stronger than a rattlesnake’s, but bites are fairly common in the U.S., with an estimated 2,500 bites treated each year.
A bite from a black widow is said to feel like a pinprick, followed by muscle pain and cramping, chills, nausea, and partial paralysis, making breathing difficult. Most victims recover without serious complications, but black widow bites have a 5% fatality rate.
Related to the black widow, the redback is found in Australia and parts of New Zealand and Southeast Asia. Its instantly recognizable by its abdomen – round with a red dorsal stripe on a black background.
The redback possesses a potent neurotoxic venom known to cause burning pain as a precursor to a condition known as latrodectism. Symptoms include pain, muscle rigidity, vomiting, and sweating. Until anti-venom for redback spider bites was introduced in the 1950s bites regularly killed people – particularly the old and young. Death rates are now at zero, and around 250 people a year receive the anti-venom each year.
Funnel-web spiders are named after the funnel-shaped webs they build as burrows or to trap prey. They are black, grow up to 5 centimeters across, and are distinguished by a shiny, lightly haired body.
The bite of the Sydney funnel-web spider and the northern tree-dwelling funnel-web spider are both potentially deadly to humans and other primates. The smaller males have the more potent venom, which contains a mix of toxins which can kill a human in anywhere from one hour to three days. Since the rise of modern first-aid techniques and reliable anti-venom, there have been no reported deaths by a funnel-web bite.
What’s the difference between most poisonous and most venomous spiders?
People often talk about the ‘most poisonous spiders’, but it’s worth taking a moment to clarify the definition of poisonous vs venomous.
The term venomous is used for any living things that bite or sting to inject their toxins.
The term poisonous is used for any living things that release toxins when they are ingested.
This means that most spiders are poisonous, whilst only a small percentage are venomous. Poisonous spiders are only harmful if you eat them, whereas venomous spiders inject toxins with a fang-like mouth-piece known as a chelicerae. It’s these venomous spiders are the ones you should be worried about and avoid all contact with!
And that’s your lot for the world’s most venomous spiders. Did any surprise you? Or have you met any of these spiders in the wild? Please do share your experiences in the comments section below. Whilst it’s not a venomous spider, the Spruce-fir moss spider is worth calling out here as it’s officially the smallest animal in the world!